You have two choices for creating a stock order: you can either create one manually, or generate an order form based off of your current stock holding and your minimum and maximum stock holding settings
Manually
Go to Stock on the left hand side -> Orders and Deliveries
Click New Purchase Order -> Name the order in the description field at the top
Search for the products you would like to add -> Fill in your ordered quantity
Save Changes -> Mark as Ordered
This will save this order form ready for you to complete when your order arrives
Automatically
Go to Stock on the left hand side -> Products
Filter by manufacturer or category if need, or search on all -> Click the yellow truck button in the bottom right
This will generate an order form for you with all products currently sitting at a stock level below your minimum stock. It will add the required amount as the number of units required to take you up to your maximum level
You can edit the required amount -> You can add additional items from the search bar at the bottom
Save Changes -> Mark as Ordered
This will save this order form ready for you to complete when your order arrives
Manually
Automatically